Introduction

The March 2003 invasion of Iraq led by the United States was conducted with anticipation of a rapid and decisive victory. Along with these dashed expectations is the growing human cost of the war. Details on coalition causalities are readily available, and are summarized below. Controversy and uncertainty surround the number of Iraqis killed by continuing actions by coalition forces and by the escalating sectarian and criminal violence. Many reports have been circulated based on mortuary tallies, reports from the coalition, and news media accounts.1, 2 These reports provide a picture of escalating violence in the areas from which the information is collected. Such methods can provide important information on the types of fatal injuries and trends. It is not possible, however, to use these methods to estimate the burden of conflict on an entire population. Only population-based survey methods can estimate deaths for an entire country.

Fortunately, methods exist to make these types of estimates for an entire population. There have been on-going efforts to further refine these methods for use in conflict situations, supported by the U.S. and Canadian governments and United Nations agencies.3

Using these established methods, we conducted a survey in 2004 that estimated 100,000 excess civilian deaths had occurred following the March 2003 invasion by coalition forces.4 As the war has continued unabated and as sectarian violence has escalated, it is likely that the death rate due to violence would have changed.5 In late 2005, we began plans to repeat the survey during 2006. The actual timing of the survey was determined by various university administrative processes and field requirements.

The goal of the survey was to measure excess deaths that could be ascribed to the on-going conflict. The term “excess deaths” describes the death rates and the number of persons dying above what would normally have been expected had the war not occurred. The normal or expected death rate was based on survey results in the period from January 1, 2002, until March 2003. This can also be considered a “baseline” death rate. In these two surveys, the expected or baseline death rate we found pre-invasion, and which we will use as the basis of this report, is very similar to estimates of the U.S. Census Bureau and the U.S. Central Intelligence Agency. 6,7

Methods

The surveyors from the School of Medicine of Al Mustansirya University in Baghdad conducted a national survey between May and July 2006. In this survey, sites were collected according to the population size and the geographic distribution in Iraq. The survey included 16 of the 18 governates in Iraq, with larger population areas having more sample sites. The sites were selected entirely at random, so all households had an equal chance of being included. The survey used a standard cluster survey method, which is a recommended method for measuring deaths in conflict situations. The survey team visited 50 randomly selected sites in Iraq, and at each site interviewed 40 households about deaths which had occurred from January 1, 2002, until the date of the interview in July 2006.We selected this time frame to compare results with our previous survey, which covered the period between January 2002 and September 2004. In all, information was collected from 1,849 households completing the survey, containing 12,801 persons. This sample size was selected to be able to statistically detect death rates with 95% probability of obtaining the correct result.When the preliminary results were reviewed, it was apparent that three clusters were misattributed. These were dropped from the data for analysis, giving a final total of 47 clusters, which are the basis of this study.

Selection of the sites

Selection of households to be interviewed must be completely random to be sure the results are free of bias. For this survey, all households had an equal chance of being selected. A series of completely random choices were made. First the location of each of the 50 clusters was chosen according the geographic distribution of the population in Iraq. This is known as the first stage of sampling in which the governates (provinces) where the survey would be conducted were selected. This sampling process went on randomly to select the town (or section of the town), the neighborhood, and then the actual house where the survey would start. This was all done using random numbers. Once the start house was selected, an interview was conducted there and then in the next 39 nearest houses. The distribution of the sample sites or clusters is shown in Table 1, which is based on the 2004 UNDP/Iraqi Ministry of Planning population estimates.8

Table 1: Province populations & cluster allocation*

Province

Mid-year 2004 population

Number of clusters

Baghdad

6,500,000

12

Ninewa

2,521,300

5

Basrah

1,981,900

3

Sulamaniyah

1,605,600

3

Thi-Qar

1,538,900

3

Babylon

1,408,700

3

Erbil

1,334,200

3

Diyala

1,271,300

3

Anbar

1,271,000

3

Salah Al-Din

976,100

2

Najaf

950,200

2

Wassit

938,700

1

Qadissiya

915,600

1

Tameem

881,500

1

Missan

848,300

1

Dahuk

817,400

0

Kerbala

741,700

1

Muthanna

569,900

0

Total

27,072,200

47

*excludes 3 clusters misattributed by the survey team

Conduct of the survey

The two survey teams consisted of two females and two males, each with one male supervisor. All were medical doctors with previous survey and community medicine experience and were fluent in English and Arabic. All were Iraqis. All were trained in the use of the questionnaire. Rules were established about how to randomly choose another area if the first one chosen was unsafe on the day of the survey visit.

In each cluster, queries were made about any household that had been present during the survey period that had ceased to exist because all members had died or left. This was done to judge the degree of “survivor bias” where only the households still “alive” could report. The survey was explained to the head of household or spouse, and their consent to participate was obtained. For ethical reasons, no names were written down, and no incentives were provided to participate.

The survey listed current household members by sex, asked about births, deaths, and migrations into and out of the household since 1 January 2002. (For more information on the survey methods and collection of data, see Appendix A and Appendix B.)

Deaths were recorded only if the person dying had lived in the household continuously for three months before the event. In cases of death, additional questions were asked in order to establish the cause and circumstances of deaths (while considering family sensitivities). At the conclusion of the interview in a household where a death was reported, the interviewers were to ask for a copy of the death certificate. In 92% of instances when this was asked, a death certificate was present.

Data Analysis

Period mortality rates were calculated based on mid-interval population and with regression models. The numbers of excess deaths (attributable rates) were estimated by subtracting the predicted values for the pre-war mortality rates from the post-invasion mortality rates in the three post-invasion periods. Mortality projections were applied to the 2004 mid-year population estimates (26,112,353) of the surveyed areas (which exclude the governates of Muthanna and Dahuk, which had been omitted through misattribution9) to establish the mortality projections.

The study received ethical approval from the Committee on Human Research of the Johns Hopkins Bloomberg School of Public Health, and the School of Medicine, Al Mustansiriya University, Baghdad.